Weather Service Report

462
FXUS65 KTWC 200404
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
904 PM MST Mon Mar 19 2018
.SYNOPSIS...High pressure will bring a strong warming trend through
Thursday. Another system will brush by mainly north of the area
later in the week for a few degrees of cooling and gusty winds, with
the best chance of showers remaining north of the area.
&&
.DISCUSSION...Latest IR/WV imagery shows flat ridging building into
the region with just a few thin cirroform clouds moving through
overnight. Temperatures are quickly cooling off this evening with
low temperatures Tuesday morning forecast to be about 5 degrees
below normal. Otherwise, warming will continue on Tuesday as ridging
continues to build in with rising heights and thicknesses. This will
result in highs about 7 to 10 degrees warmer than today. Current
forecast in good shape, no updates this evening. See previous
forecast discussion below for additional information.
&&
.AVIATION...Valid through 21/06Z.
Generally clear skies through the forecast period with SCT clouds
above 20k ft AGL possible. SFC winds generally variable 10 kts or
less thru the period, though they will tend to be more focused
from a WLY-NWLY direction during the afternoon.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Dry with a warming trend through Thursday. A Pacific
storm system will bring a slight chance of showers mainly north of
Tucson Thursday night into Friday, as well as cooler temperatures on
Friday. Highs next weekend will be at or slightly above normal. 20-
foot winds will mainly be less than 15 mph into Wednesday. Some
gusty southwest afternoon winds Thursday into Saturday.
&&
.CLIMATE...A strong ridge of high pressure aloft by mid-week will
bring record or near record highs on Thursday for portions of
southeast Arizona. Not everyone will be near record highs. However,
the Tucson International Airport forecast high temperature of 90
degrees for Thursday, March 22 would tie the record high of 90
degrees set in 1990. The historical average first 90 degree date of
the year in Tucson is April 9. The average date since 1980 has been
April 1 while in the 21st century the average first 90 degree
occurrence has been March 25.
&&
.PREV DISCUSSION...As high pressure builds in from the west this
afternoon, the expected warming trend has arrived with temperatures
up 4 to 7 degrees compared to yesterday. Rather dry as well, with
precipitable water below 1/4 of an inch on GOES total precipitable
water estimates, and surface dew points cratering in the single
digits and teens this afternoon (down 15 to 25 degrees over the past
24 hours).
Strong warming will continue through mid week; by Wednesday
temperatures will be up 20-25 degrees compared to yesterday. With
the current pattern the ridge axis will have shifted just east of
the area Thursday, but thicknesses still support temperatures even
higher than Wednesday with valley locations typically slower to
respond this time of year. At this point we have a better than 65
percent chance of the first 90 of the year at Tucson International
Thursday.
Some interesting developments in the eastern Pacific as a strong low
off the northern California coast is drawn northward into higher
latitude flow, merging with a system digging down the Canadian coast
over the next 72 hours. Unfortunately only a weak southern split is
supported with as this system pushes into the region late in the
week. That adds up to 10-15 degrees of cooling with gusty winds and
limited precip chances.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Lader/Meyer/Rasmussen
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